The computer, information, and entertainment industries produce and consume vast quantities of disk-shaped substrates, such as silicon wafers, and aluminum, plastic, glass, or other multi-layered disks. In the fabrication of semiconductors, silicon wafers are processed through multiple fabrication steps which can include repeated application and removal of various conductive, non-conductive and semiconductive materials before the resulting microcircuits are complete and separated into individual dies. Aluminum, glass, and other composites disks substrates are typically overcoated with magnetic, optical, or magneto-optical materials in the fabrication of each HDDs, CDs, DVDs, and other such products.
Substrates typically need to be buffed, polished, etched, cleaned, and otherwise prepared repeatedly during the fabrication process. This is true for both wafer and disk substrates. In the semiconductor manufacturing industry, for example, integrated circuit devices designed of more complex, and more precise multi-layered structures require highly clean and prepared surfaces. In the field of magnetic and optical media disks, ever-increasing density translates into exacting requirements for disk cleaning and preparation. Defects resulting from improper, incomplete, or insufficient substrate buffing, polishing, cleaning, or other preparation produces decreased yield and increased time and cost.
Disk cascade scrubber arrangements are known that seek to process a plurality of disks in a rapid and efficient manner. See, for example, the disk cascade scrubber described in U.S. Pat. No. 6,525,835. In such a system, a track is provided that is configured to support a disk in a vertical orientation between pairs of rollers, with a pair of guiding rollers provided to transition the disk into vertical orientation along the track between the pairs of rollers.
FIGS. 1a and 1b illustrate components of a substrate drive assembly 131 in accordance with a known design such as that shown in U.S. Pat. No. 6,625,835. FIG. 1a shows a side view of the substrate drive assembly 131 with representative large substrates 108 shown. For ease of illustration, the substrates 108 are depicted as disks.
The substrates 108 are positioned in a vertical orientation and supported at two points on the edge of the substrate 108 by guiding rollers 122. These guiding rollers 122 are suspended above the substrate drive assembly 131 by guiding roller arms 154 and connected by roller arm brackets to the roller drive chain 120. The roller drive chain 120 is configured as an endless chain. The roller drive chain 120 is connected by sprockets to parallel shafts 134 and 136, one of which drives the rotation of the roller drive chain 120. Roller drive chain 120 can be constructed of stainless steel, plastic, or other low particulate-generating materials. The roller drive chain 120 can also be configured as a belt drive and connected to the two parallel shafts 134 and 136 by pulleys.
The guiding rollers 122 can be free-wheeling. These guiding rollers 122 are in contact with the substrate 108 edge and provide some lateral support. The guiding rollers 122 freely spin on the support arms 154 and offer no resistance to the rotation of the substrates 108. The roller drive chain 120 travels in the direction 123b which applies force to the substrates 108 through the guiding rollers 122 and cause the travel of the substrates 108 from one end to the other of the cascade scrubber assembly.
The substrates 108 are positioned on an edge rotational drive belt 124 or track configured to support the substrates 108 in the vertical orientation between the rollers. The edge rotational drive belt 124 is a track defining the path of the substrates 108 transitioning through the cascade scrubber assembly and can be an endless loop belt. The edge rotational drive belt 124 is connected to two parallel shafts 134 and 136, one of which drives the rotation of the edge rotational drive belt 124. The edge rotational drive belt 124 may travel in the direction 123a which is opposite the direction of travel 123b of the roller drive chain 120. The rotation of the edge rotational drive belt 134 applies a rotational force to the substrates 108 which are positioned between pairs of guiding rollers 122. Thus, as can be seen in FIG. 1a, the substrates 108, positioned on the edge rotational drive belt 124 which is rotating in direction 123a, will be caused to rotate in a clockwise direction in their position between pairs of free-wheeling guiding rollers 122. Roller drive chain 120, traveling in direction 123b, transitions the rotating substrates 108 from left to right as represented in FIG. 1a. 
FIG. 1b shows the use of the system FIG. 1a with a smaller size substrate 108 than that shown in FIG. 1a. The substrates 108 in FIG. 1b are positioned on the edge rotational drive belt 124 between free-wheeling guiding rollers 122 suspended over edge rotational drive belt 124 and guiding roller arms 154. Because the substrates 108 in FIG. 1b are smaller than those shown in FIG. 1a, the spacing of the guiding rollers 122 is necessarily closer. The guiding roller arms 154 are configured such that the two most common substrate 108 sizes can be processed by the cascade scrubber system 100 without having to change or re-configure the substrate drive assembly 131 to accommodate the two differently sized substrates. As can be seen in FIGS. 1a and 1b, the substrates 108 are positioned between pairs of guiding rollers 122. The guiding roller arms 154 are configured to accept a larger substrate between a wide-spaced pair of guiding arms 121a and a smaller substrate between a narrowly-spaced pair of guiding arms 121b on the same roller drive chain 120. The size of the substrates 108 determines which pairs of guiding rollers 122 are selected to support the substrate 108.
In FIG. 1b, the height of the edge rotational drive belt 124 is adjustable. In processing the smaller sized substrates 108, the edge rotational drive belt 124 is raised to a position to maintain the diameter of the substrate 108 in the nip of the rollers 110. Because the guiding roller support arms 154 are configured to accept large or small substrates 108, as described above, no similar adjustment to the roller drive chain 120 is required.
There is an increasing need to be able to process wafers or substrates of many different sizes. Although U.S. Pat. No. 6,625,835 describes that the wafers or substrates could be of any size, this is difficult to achieve in practice with the arrangement depicted in FIGS. 1a and 1b. This is because the guiding roller arms 154 extend in a non-offset, vertical direction away from the roller drive chain 120. Hence, as depicted in FIGS. 1a and 1b, there are a limited number of positions at which the guiding roller arms 154 can be attached to the roller drive chain 120. The straight guiding roller arms 154 are thus positioned and attached to the roller drive chain 120 only at the pins connecting the links in the roller drive chain 120. There is therefore a lack of flexibility in the available positioning of the guiding roller arm 154, such that the distance between the guiding roller arms 154 is constrained to be some multiple of the distance between the pins of the links in the roller drive chain 120. Moreover, with the increasing number of different sized substrates or disks that need to be processed, greater flexibility is required to process these different sized substrates.